In many situations or applications where electric motors are used to do useful work, a direct current electric motor is utilized to move an object or objects in opposite directions depending on the polarity of the voltage applied to the motor. For example, if a motor operates a rotary device which in turn controls some mechanical structure, as for example a window operator which rotates to open and close a window, a direct current of one polarity will cause a motor connected to turn the window operator to rotate in one direction, and thereby open the window, while electric current of the opposite polarity will cause the motor to rotate in the opposite direction to close the window. Accordingly, systems for such an application need to have a mechanism to determine readily and conveniently which polarity of voltage is to be applied to the motor to cause the operation of the closure in the manner selected by the operator. A polarity fixed system for window operation in particular suffers from one inherent difficulty in that there is no standard for the mechanical operators of windows as to which direction a window operator should turn to open or close the window. Thus some windows are manufactured where a clockwise operation of the operator handle opens the window while some other windows are constructed such that a clockwise operation of the operator closes the window. Accordingly, a device for remote window operations must be adaptable to the particular windows to be utilized in the application. One way to achieve an adaptation for this problem in an electric remote window operating sytem is to have a switch or a jumper which can be installed into the system operating the motor controlling the window so that the polarity of operation of the window can be determined. Such a solution, however, suffers from deficiencies in that it is relatively expensive, and may require skilled installation, and may prove difficult to use if windows of opposite directional control are operated by a common control system.
The prior art is generally cognizant of the concept of operating motors with microprocessor or digital control, with control being responsive to the position of the motor control device. For example in U.S. Pat. No. 4,431,954, a microprocessor controls motor operation for windshield wipers with the position of the windshield wipers at any given time being determined by position sensors. Similarly U.S. Pat. No. 3,792,332, provides an interface for multiplex motor control systems in which a microprocessor or other control box is used to operate a number of motive devices. Other window or closure operating systems are illustrated in U.S. Pat. No. 3,781,622 and U.S. Pat. No. 2,994,525.
The broad concept of sensing the electromagnetic force from motor operation as a means of controlling motor operation is not new in and of itself. For example, the disclosures of U.S. Pat. No. 4,119,899 and U.S. Pat. No. 4,358,718, disclose motor operating devices for direct current motors which are, to some degree, responsive to the counter electromotive voltage induced in the direct current motors. Both of these systems operate with conventional direct current voltage supplies.